Chapter 21, Problem 21.103SP

Interpretation Introduction

Interpretation:

The reaction that occurs when ${\text{Y(OH)}}_3$ sol becomes a gel has to be described and chemical formula of ceramic obtained when dried and sintered has to be determined.

Concept introduction:

• Sol is a colloidal dispersion consisting of extremely fine particles having a diameter of only $0.001-0.1\mu m$, in which elimination of water takes place and forms oxygen bridges between metal atoms.
• Sol-gel method: Metal alkoxide, (obtained from metal and alcohol) undergoes hydrolysis and yields metal hydroxide. These metal hydroxides are known as sol and they are fine particle. Further, metal hydroxides combined together to form oxygen bridges by eliminating water. Sol linked together through a three dimensional network of oxygen bridges in which is sol is converted to a material known as gel. By heating water and solvents are removed to get metal oxide.
• Particles of the sol link together through a three dimensional network of oxygen bridges and the sol is converted to a more rigid gelatin like material called gel.